In general, in a case where positioning of a processing tool with high accuracy is required, and processing (e.g., drilling a hole) in which a processing reaction (reactive) force is generated is performed, the position of the tip end of the processing tool is deviated due to the processing reaction force, so that accuracy of a processing position is reduced and a processing target (hereinafter will be referred to as a workpiece) is damaged. To avoid this, the processing tool attached on the tip end of a positioning device is pressed against the workpiece with a force (hereinafter will also be referred to as a pressing force) that is equal to or larger than the processing reaction force, prior to the processing. At this time, flexure of the positioning device occurs due to a counteracting force of the pressing force, and thereby the position of the tip end of the processing tool is deviated. This position deviation (position gap) negatively affects accuracy of the processing position.
Conventionally, to compensate the flexure of the positioning device, there is a method in which a flexure amount of the positioning device is calculated from a force applied to a positioning controller, by use of a stiffness value of the positioning device (see, e.g., Patent Literature 1).
In an exemplary prior art, a force sensor is attached on the tip end of an arm of a robot, a force applied to a member held by the robot and a flexure of the member occurring due to the force are detected by use of the force sensor, and the position of the member held by the robot is compensated (e.g., see Patent Literature 2). Also, there is a method in which a feeding device mounted on the tip end of an arm together with a machining tool is secured to a support base on which a workpiece is placed, during processing performed by a drilling robot (e.g., see Patent Literature 3).